Walter was against militarism
he was against militarism because he love Germany and was deeply troubled by the outbreak of World War I. As patriotism swept the U.S. and all things German became repulsive, Rauschenbusch's popularity declined, and even more when, after the war, liberalism came under attack by neo-orthodox thinkers like Karl Barth and Reinhold Niebuhr.
Though subsequent historical events showed Rauschenbusch to be overly optimistic, he still towers above other advocates of the social gospel. "His writings," said Martin Luther King, Jr., "left an indelible imprint on my thinking," and his understanding of the kingdom of God continues to appeal to those who want to combine evangelical passion with social justice.